22 SELA.CHII: RAIiE. — V. 



21. TORPEDO Dumeril. 

 30. T. occidentalis Storer. Torpedo. Cramp-fish. Numb- 

 fish. Black, with obscure darker blotches ; spiracles with entire 

 «dges. L. 3 to 5 feet. Cape Cod S. ; not common. 



Family XVI. DASYATIDuS!. (The Sting-Rays.) 



Disk broad, the pectorals confluent anteriorly, forming tip of 

 snout ; tail, usually whip-like, sometimes short and stout, with or 

 without fins, but never with two dorsals. Tail usually armed with 

 a sharp, retrorsely serrate spine above, near the base (this often 

 duphcated and sometimes wanting) : ventral fins entire. Skin 

 smooth or variously rough, the adult roughest. Mouth small, with 

 small teeth. Sexes similar. Genera 10, species 50, in most 

 warm seas. The large spine or " sting " on the tail in most species 

 may inflict a dangerous wound. 



a. Tall slender, whip-Uke, without caudal fin, longer than the disk; "sting" 



on tail strong Dastatis, 22. 



<m. Tail verj' slender and short, shoi'ter than the very broad disk : sting 

 minute or wanting Pteeoplatea, 23. 



22. DASYATIS Rafinesque. (Trygon Adanson.) 

 (SacnJf, shaggy or rough ; ^aris, skate.) 

 a. Tail with a fold on its lower margin only, the upper edge rounded. 



31. D. centrurus (Mitohill). Common Sting-Ray. Clam- 

 Cracker. Stingaree. Snout not prominent ; disk a httle wider 

 than long ; tail usually not quite twice length of disk. Adult 

 with some stellate tubercles on back and tail. Color olive-brown. 

 L. 12 feet. Cape CoA.S., common, {nivrpov, spine; ovpa, tail.) 

 aa. Tail with a fold of skin on its upper as well as lower margin. 



32. D.'say (Le Sueur). Southern Sting-Rat. Whip- 

 PAREE. Snout not prominent ; disk a little wider than lone ; tail 

 nearly twice length of disk. Body and tail without large spines. 

 N. Y., S. (To Thomas Say, a distinguished zoologist.) 



23. PTEROPLATEA, MuUer & Henle. 



33. P. maclura (Le Sueur). Butterfly Rat. Disk nearlv 

 twice as broad as long, three times as long as tail; stino- on tail 

 usually obsolete. Olive-brown, finely marbled and speckled : tail 

 with four dark blotches : iront edge of disk with pale half-circular 

 spots. Va. S. (To William Maclure.) 



Family XVII. AETOBATID^. (The Eagle Rays.) 

 Pectoral fins interrupted, reappearing on tip of snout as one or 

 two detached appendages or cephalic fins ; skull somewhat elevated 

 so that eyes and spiracles are lateral ; teeth large, flat, hexanfrular 



